1. Technical Field
The invention relates generally to high semiconductor chip packaging, and more particularly, to a method of producing flip-chip joinable contact pads on a surface of a chip carrier.
2. Related Art
The related art provides flip-chip assemblies including a substrate having plated-on attach pads for joining semiconductor chips or other substrates. Ball Grid Array (BGA) chip packages are typically constructed with a substrate (e.g., chip carrier) that supports the integrated circuit and which has a substrate core that is constructed with conventional printed circuit board processes, such as lamination. The exterior planar surfaces i.e., top and bottom surfaces) of the substrate each contain a plurality of exposed plated-on metal attach pads (e.g. plated-on copper pads). Typically, a solder ball is placed onto each exposed attach pad. The solder balls are then heated and reflowed to bond the balls to the plated-on metal attach pads. Each of the plated-on attach pads is then physically and electrically connected through the solder ball to a corresponding metallized pad on the chip's surface or on the surface of another substrate.
The related art forms the attach pads on the exterior surfaces of a substrate by employing metal plating techniques (e.g., electroless copper plating followed by Ni/Au plating). The metallization process typically employed to produce the plated-on attach pads of the related art comprises external plating steps and is relatively time consuming and expensive.